This invention relates to a novel light-colored seasoning liquor and a method for producing the same.
In the conventional method for preparing a seasoning liquor by using the protein sources of soybean and wheat, the protein is hydrolyzed so as to produce the seasoning liquor. For example, the protein is hydrolyzed into amino acids by treating it with a mineral acid such as hydrochloric acid at an elevated temperature and the decomposed product is then neutralized and refined to obtain an amino acid seasoning liquor. In another method, the amino-bonds of protein are partially cut by hydrochloric acid and the product is then subjected to fermentation by adding soy sauce mash or draft soy sauce so as to produce a new-type soy sauce. In these methods, corn protein is sometimes utilized to some extent and the rate of decomposition or utilization of protein is improved as compared with the conventional totally fermenting method, and further, the production period is much reduced. However, the methods are accompanied with the formation of disagreeable substances such as levulinic acid and formic acid because the carbohydrates mixed in vegetable protein are easily hydrolyzed as compared with the protein itself, and the carbohydrates are decomposed to excess.
While, in the production of soy sauce by the conventional totally fermenting method, soybean and wheat are used as the main nitrogen sources. That is, after the heat treatment of the mixture of soybean and wheat, the mixture is inoculated with koji-mold (seed culture) and it is then incubated to obtain koji (mold preparation containing developed mycelium of koji-mold) and the fermentable mash is prepared by adding a saline solution to the koji. Thus the protein and starch contained in koji-substrate are decomposed by the protease and amylase in the koji, and further, fermentation is caused to occur by lactic acid bacteria and yeast in the koji. After the ripening of the fermenting mash, soy sauce is obtained. This method is, however, economically disadvantageous in that several months are necessary for the fermentation, in addition, the rate of utilization of the protein and starch in the employed soybean and wheat is quite low. Further, though this method is not accompanied by the formation of disagreeable substances such as levulinic acid, there is another defect that the nitrogen concentration in the product is low as compared with that of the product of hydrolyzing method.
Meanwhile, corn is more widely used for animal feed than soybean and wheat as the nitrogen source, and it is produced in large quantities at low cost. Further, the amino acid composition of corn protein very much resembles those of the protein of soybean and wheat. However, it is very hard to decompose the corn protein by enzyme so that the development of enzymatic digestion and fermentation method for producing a seasoning liquor has long been sought.
In order to eliminate the above-described defects present in the conventional art methods and to develop a novel method for producing seasoning liquor of preferable quality by using corn protein, the inventors of this application have carried out extensive studies, and as the result, the inventors have succeeded in developing a novel seasoning liquor and a method for producing the same. The seasoning liquor is prepared by decomposing the protein contained in corn protein to amino acids or peptides and by fermenting and ripening the material in a very short period of about 30 days, and the produced seasoning liquor is quite good in savor and color without containing disagreeable substances such as levulinic acid and is high in nitrogen concentration as compared with the conventional soy sauce. Details of this seasoning liquor and the producing method are disclosed in a co-pending patent application entitled "Novel Seasoning Liquor and Method for Producing the Same" as filed on the same day as United States Serial No. 819,203 the present application. The seasoning liquor disclosed in the specification of the above application has a color of dark reddish brown which corresponds to the color of dark brown soy sauce (koiguchi soy sauce).
As it is known, however, that there are other kinds of soy sauces such as light-colored soy sauce (usuguchi soy sauce) and white soy sauce (shiro soy sauce), a light-colored product of a seasoning liquor has also been desired so as to meet the taste or demand of users. Further, with regard to the conventional light-colored soy sauce, not only the color is light but also the savor is generally thin. For example, typical analysis data of a light-colored soy sauce are as follows:
Total nitrogen: --1.0-1.3% PA1 formol nitrogen: --0.6-0.7% PA1 alcohol: --0.1-1.0% PA1 sugar: --2-4% PA1 sodium chloride: --17-18% PA1 pH: --4.7-4.9 PA1 buffer index: --1.2-1.4